Migrate from forge.lthn.ai deps to dappco.re. Replace os, strings,
path/filepath with Core primitives. OnStartup returns core.Result.
Service factory returns core.Result.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Module path changed from forge.lthn.ai/core/go-config to forge.lthn.ai/core/config.
Package name remains "config" — only the module path changed.
Co-Authored-By: Virgil <virgil@lethean.io>